Meggitt VM600 - The TCP Section; The GLOBAL Section

VM600 networking manual MAVM600-NET/E 9 - 3
Edition 9 - February 2018
Definition of registers
SETTING UP A MODBUS CONNECTION (CPUM SW VERSION 071 OR LATER)
9.2.2 The TCP section
The TCP section shall have the settings shown in Table 9-3.
9.2.3 The GLOBAL section
Although 32-bit values were not part of the original Modbus specification, extensions have
been implemented which allow 32-bit values to be retrieved using Modbus and two
consecutive registers. The byte-order of data contained in the two consecutive registers,
however, has not been standardised, so the user must specify the byte-order they prefer. The
user has the ability to select 32-bit floating-point values and 32-bit long word values to be
retrieved, in different formats.
NOTE: The GLOBAL section is optional.
The 32-bit floating point values can have the settings shown in Table 9-4. If this global section
setting is missing, the floating point values will have the default order type FM1 (the most
commonly encountered type).
The 32-bit long word values can have the settings shown in Table 9-5. If this section is
missing, the long word values will have the default order type LB.
Table 9-3: TCP section settings
TCP section
setting
Default
value
Allowed values
ENABLE N Y/N
PORT 502 0 to 65535
Table 9-4: GLOBAL section settings
GLOBAL section setting
Default
value
Allowed values
DEFAULT_FLOAT_ORDER FM1 FB/FL/FM1/FM2
where
FB: Float (32-bit) ordered as ‘big endian’. For example, ABCD.
FL: Float (32-bit) ordered as ‘little endian’. For example, DCBA.
FM1: Float (32-bit) ordered as ‘mixed endian 1’. For example, CDBA.
FM2: Float (32-bit) ordered as ‘mixed endian 2’. For example, BADC.
Table 9-5: GLOBAL section settings
GLOBAL section setting
Default
value
Allowed values
DEFAULT_LONG_ORDER LB LB/LL/LM1/LM2
where
LB: Long word (32-bit) ordered as ‘big endian’. For example, ABCD.
LL: Long word (32-bit) ordered as ‘little endian’. For example, DCBA.
LM1: Long word (32-bit) ordered as ‘mixed endian 1’. For example, CDBA.
LM2: Long word (32-bit) ordered as ‘mixed endian 2’. For example, BADC.